Sound-transforming apparatus



- June 17, 1930- A. A. A. K ALMEIJER 1,765,275

SOUND TRANSFORMING APPARATI JS Filed Jan. 16, 1 928 3 Sheets-Sheet 1 AZTo/wy June 17. 1930. A. A. M. A. KALMEIJER 1,765,276

scum) TRANSFORMING APPARATUS- Filed Jan. 16, 1928 3 Sheets-Sheet 2 71/672 far:

June 17, 1930. A. A. M. A. KALMEIJER 1,765,276

SOUND TRANSFORMING APPARATUS Fi led Jan. 16, 1928 3 Sheets-Sheet s Patented June 17, 1930 UNITED STATES PATENT OFFICE ADBIANUS Anuonnus iunmus ANTONIUS x'nnmnrma, or 1mm HAGUE,- 1

NETHERLANDS SOUND-TRANSFORMING APPARATUS Application filed January 16, 1928, serial l l'o. 247,215, and in the Netherlands December 80, 1927.

This invention relates to apparatus for relative transformation of electrical and mechanical energy into sound vibrations, such as a telephone receiver or transmitter,

5 gramophone sound-box, loudspeaker, etc.

There are various ty es' of loudspeakers and the like, the best of which is today the loudspeaker with a conical diaphragm, whether large or small, vibrated by electromagnetic, electrostatic or electrodynamic means.

According to the well-known theory, the diaphragm must have special dimensions, a predetermined apex angle and a weight as light as possible. Furthermore the diaphragm must be very stiff, and for that reason a compromise between lightness and stiffness is essential, so that a maximum effect is unobtainablc.

Moreover, the diaphragm must move bodily, or as a whole, like a piston. At the lowor frequencies this can be practically carried out; but at the mean and higher frequencies, however, a serious difliculty is encountered because the diaphragm is then subjected to undesirable deformations due to the fact thatthe driving point of the diaphragm has already commenced to move back while the vibration is still travelling toward the edge of the diaphragm, which gives rise to an oppositely-directed vibration. This effect is more pronounced the more the diameter of the diaphragm increases.

For these reasons the large-area diaphragms are gradually being replaced by small ones which are driven by electrodynamic means. Such loudspeakers are, therefore, .very costly and not available for the person of average means.

I have also discovered that a very great deal of trouble arises from the usual onepoint drive, and the purpose of my invention is to provide useful means, suitable for musical and other acoustic reproduction, etc., which do not possess the various drawbacks of the known types, and which may be combined with any. driving or driven vibrating means, whether of electro-magnetic, electrodynamic, electrostatic, or other nature.

According to my invention, I make use of an acoustic means, member or devlce supported at oppositely-located points and having-in a direction across connecting lines between the said points-different natural periods, and of means for exerting a vibrating force at a plurality of points situated between the opposite supporting points of the acoustic means, which vibrating means is positively connected to the acoustic means. With this principle inmind, various dif-' ferent structural embodiments are possible, and in the further description of the invention a few of them are described and illustrated.

The acoustic means, as well as the vibration-exerting means, may consist of a single member or of a plurality of members; in the case of a single acoustlc member and a single vibrating member, the connection between these two members must be at a plurality of points, for instance along a line.

The acoustic member according to the invention need not have the form of a circle but may be of any other form, provided there is a possibility of connecting the driving member or members to the vibrating member or members at points or along lines situated between opposite supporting points or' lines of the acoustic member, and provided the latter has different natural periods at the contacting points with the vibrating member or members. i

It is not strictly necessary to make the acoustic member responsive to all occurring frequencies to be reproduced, as there are cases in which only a part of the said frequencies are to be reproduced in the present improved manner.

My invention relates, therefore, to acoustic devices of the kind referred to, regardless of their precise character, by which driving means or means to be driven are connected ata plurality of points or along a line, etc., to an acoustic'member supported 95 at either'side at some distance from the connecting points, line or lines or the like.

It will be apparent from the foregoing that, according to the invention, the acoustic member is clamped or otherwise supported in .tensioned or untensioned condition at those points where the nodal points of the various natural periods are situated, and that it is connected at points therebetween Sphere the vibration loops are situated) to t e drivin or driven member exerting the vibrating orce. In a practical embodiment,

these connecting or excitation points are located midway the o posite supportin points; but they may, owever, be loca at other places between the supporting vibration ener necting point or v The connection of the driving member or of the member to be driven to the acoustic member may be effected in various ways, for instance, alon a series of points or a single line; the riving force may be. applied directly or indirectly by means of an electromagnetic or electrodynamic device such as an armature or other vibratory member through the intermediary of a cone, a cylinder or other means, provided it is connected to the acoustic member.

The acoustic member according to the invention may consistof a flat or curved plate or disk clamped or otherwise supported at its circumference at different distances from one or more connecting points or from a connecting line within its said circumference; and this late, between its circumference and the a oresaid line, is connected to the ed e of a cone, an excitation coil or other riving member, or member to be dr1ven, or vice versa. It may, alternatively, be secured at equal distances from the conints or connecting line; and it may, at' di erent points, be of different thicknesses, tensions or materials.

The acoustic member'may further consist of a single part or a plurality of separate or interconnected parts, the tension or the driving point of which may be adjustable for the pur se of regulating the natural periods; an for the same purpose, the pressure-or the tensile stress, or .both, exerted on the acoustic member by the driving member or the member to be driven may be adjustable.

The said member ma be constructed as an ordinary or truncated straight or oblique cone which, at the ed or wide end and at the top or narrow en is clamped in place or otherwise supported, and is connected at different points of its surface to'a second cone, a cylinder or other member receiving or delivering the vibrating forces, or vice versa.

In order to obtain the same speed of translation of the acoustic frequencies, the

drivin member or the member to be driven' is pre erably made of the same material as the acoustic member.

The single acoustic member or the multipart acoustic member maybe manufactured and sold separately, and then mounted so as to be supported along the nodal points of different natural eriods and to be energized at the locus of the vibration loops for delivering or receiving energy, or vice versa. Moreover, such member need not be driven just midway between the nodal points at which it is supported, clamped or otherwise attached, but ma be driven at other places where vibration oops are formed.

The improved acoustic member may be constructed in various ways. For example,

if a tone range is desired extending from.

3233 to 4138 vibrations per second, then an acoustic member may be used which is obtained by tracing on a suitable sheet of paper or the like two eccentric circles, one ying free within the other, and cutting away the parts located outside the part bounded by the said circles to such an extent that the ring thus formed may be clamped or supported along the' circles Thus each radius of this ring has another natural period If desired, predetermined tones may in this way be reproduced in a more or less pronounced manner by maki the sector of the acoustic member concern relatively too small or too lar e, or by removing it or damping it, or y giving it more o'r'less tension. A similar result may .be obtained by clamping the acoustic member at difi'erent points in adjustable manner or by constructing it of a plurality of parts which are then permanently connected to the single drivin or driven member, or to the multi-part riving or driven member,

and they mayindividually be fastened in place and tuned so as to deliver their energy to a suitable acoustic member according to the correct tone curve.

The number of octaves desired to be reproduced ma be divided into frequency series, each of wh he difierent acoustic members may be arranged or directed in various ways in order that the reproduction of predetermined harmonics may-be taken into account in obtaining a rich sound composed of fundamental notes, harmonics, overtones, etc. T

A very good result may be obtained if the material of the acoustic member, as regards 'its nature, is suited to that of the driving or driven member, so as to harmonize the eed of the mainly-Ion itudinal waves in t 6 driving member wit the speed of the transverse resonant waves in the acoustic member. The same material might advantagreously be used for both. i

be supporting means, i. e., the clamping ich series is re roduced by a sep arate acoustic member.

means for the acoustic member, may be made heavier or lighter than the said member itself according to the construction used and its purpose. Taking into account the acoustic requirements, the acoustic member may be driven at a plurality of separate points, wherefore it can be given a very large surface area; and it is also possible to drive one and the same acoustic member by a plurality of diflerently or correspondingly energized driving members, which may be advantageous in some cases. The acoustic member may then be supported or damped according to the series of nodal points arising.

Conversely, the acoustic member might be supported at the place where it is driven and be driven at the place where it is supported, if the circumstances will allow this. Both methods may also be combined while taking into account resonance effects,

The device according to themvention may serve 'also as a microphone or sound receiver,

' means being provided for influencing the acoustic member between its supporting points by spoken sound or in some other manner; a plurality of electromagnetic or other receiving or transmitting devices according to the invention may be connected in parallel or in series. 0

Finally, the acoustic member, which, as stated, can be placed on the market separately, may have the form of a truncated cone or other suitable shape and may or may not be equipped with means for connecting it to 'one or more driving members, or it may simply have marks for mdicatmg the po1nts of connectlon to one or more drivlng or t driven members.

The invention will be more fully understood with reference to the accompanying drawings, illustrating various embodlments thereof, by way ofexample, in a more or less diagrammatic manner.

Figure 1 is a vertical section of one form of the device or apparatus according to the invention;

Fig. 2 is a modification thereof;

Fig.- 3 is an elevation of the device represented-in Fig. 2; 7

Fig. 4 is a vertical section of another modified construction;

Fig. 5 is an elevation of Fig. 4;

Fig. 6 is an elevation of a special embodiment;

Fig. 6 is a development of a section taken along the circular line in Fig. 6;

Fig. 7 illustrates stlll another embodiment;

Fig. 8 is a face view of a device having an oval acoustic member;

for effecting excitation by linear vibrating means; p

Fig. 10 is a face view of an acoustic member divided into a plurality of sectors;

9 is a perspective view of a device Fig. 11 is a vertical section of a receiver to be used as part of a horn speaker or of an ear-phone, constructed in accordance with the invention;

Fig. 12 shows a gramophone sound-box embodying the invention;

Fig. 13 shows a microphone or transmitter constructed according to the invention.

According to Fig. 1, the acoustic member comprises a cone 1 of paper, thinwood, celluloid or any other suitable material, such as that frequently used in making ordinary loudspeaker diaphragms, which cone may be pointed or, as shown, may be truncated and supported by a rigid arm 2. The edge of the cone is clamped in a rigid-ring 3 contacting therewith along a line.

At the middle of its generatrices, the cone 1 is connected along the line 7 to and driven by a vibrating cone 4 connected by means of a rod 5 to an electromagnetic or other vibrationor oscillation-producing device 6. The material of the two cones is so chosen as .to be in harmony with the speed of the vibrations or oscillations of thedriving cone 4 which are mainly longitudinal, and with the speed of the resonant transverse vibrations of the acoustic member or cone 1. The thickness of the cone 1 increases circumferentially from the top downwardly according to the desired series of natural periods. The device may be so constructed that the cone 4 forms a vibrating member which is supported in a novel manner by the acoustic member.

Figs. 2 and 3 differ from Fig. 1 merely in that the cone 1 has its axis disalined from that of cone 4, the'latter being of right-circular form, as before, whereas cone 1 in this instance is oblique. The driving line is indicated at 7.

In Figs. 4 and 5, radial lines 8 are traced on the flat, or almost flat, acoustic member 1 at either side of the circular driving line 7; the angular distances between successive 7 lines being equal, while the length of every second succeeding line is doubled according to the chosen number of octaves .at the left and right of the axis of symmetry 9. The lines 10 and 11, along which the acoustic member is bounded and fixed surround the corresponding curved margins of screens 12,

13, while the vibrating or oscillating device 6 is located inside the driving cone 4. The screen 13 ma be used as a baflle board.

The embo iment according to Figs. 6 and 6 is adopted when the thickness of the acoustic member 1 decreases stepwise along the connecting line 7 in accordance with the various frequencies to be reproduced. Moreover, the constructions shown in Figs. 5 and 6 may depart from the flat shape, and each octave curve may be accurately constggiicted by subdividing the sector concerned ar a-by giving the construction lines the correspond ing lengths, taking into account variations which may be eventually desired.

. Fig. 7 illustrates how the invention may be a plied to a cylindrical acoustic member 1 of constant thickness by connecting a vibrating diaphragm 14 to the said member alongthe circumferential line 7, and securing t e nonparallel edges 15, of the cylinder in some suitable manner not shown. The active lengths of the generatrices are roportional to diflerent natural periods. he thickness of the material is assumed to be constant in Figs. 2-5 and 710.

Fig. 8 shows an oval acoustic member 1" vibrated along a closed connecting or driving curve 7 such member being clamped at 16 along a straight line and at 17 along a curve. Moreover, the curved driving line 7 need not be a circle but may have other forms, as in Figs. 8 and 9. I

Fig. 9 shows a flat acoustic member 1 of constant thickness clamped along curved lines at the top at 18 and at the bottom at 19, and vibrated midway these curved lines at a series of points located on the driving line 7 b means of a driving or driven unit mounte in a suitable box 20. In this arrangement the circular driving line has been developed to form a straight line. This embOdlllQIlt may also be used for transmitting soun In Fig. 10, the acoustic member 1" is shown as comprising a plurality of substantially-trian ularsectors which are vibrated alon the riving line 7 and are supported by t e arm 2 and ring'3, to which latter theyhave a suspension connection by means of adjustable bolts 3 which enable the ten- $131111 of said sectors tobe regulated individu 1 11? all these embodiments, the vibrating drive may be either positive or negative, or a combination thereof, and maybe effected by pressure or-tensile stress or both.

Fig. 11 illustrates the application of the invention to an ear-phone or to a tele hone receiver for a horn-speaker. 22 is a suitable acoustic member having different thicknesses which increase circumferentially from the top downwardly, and which is supported at 23 and 24 and vibrated by a cone 25 which, by means of aniron armature, is under electromagnetic influence.

Fig. 12 shows the invention applied to a gramophone sound-box. The stylus bar 27 vibrates the cone 25 which is connected at 7 to an acoustic member 22 supported at 23 and 24 and'shaped-as in Fig. 11.

Finally, Fig. 13 shows a transmitter comprising an .acousticmember 1 as in Fig. 1, I

but designed to be activated by spoken'sound and connected at 7 to a vibrating cone 4 for altering the capacity of a small condenser 28 which, by means of connecting terminals places and having, in a direction across connecting lines between the said places, difierent' natural periods; and means connected to the acoustiemeans for exerting a vibrating force thereon at a plurality of oints located between said oppositely-locate places of the resonant-acoustic means.

2. Apparatus for effecting transformation of electrical and mechanical energy into sound vibrations, comprising a resonant acoustic member supportedat oppositelylocated nodal points of natural vibrations; said member having, in a direction across connecting lines between such points, different natural periods within the. acoustic range; and means connected to the acoustic member for exerti a vibrating force thereon at a plurality 2% vibration loop-forming points between said nodal points.

3. Apparatus for efiecting transformation of electrical and mechanical energy into sound vibrations, comprising a resonant acoustic member supported along two circular lines,-one circle within the'other; said member having, in a direction across connectin naturafi periods .within thev acoustic range; and means positively contacting with the acoustic member for exerting a vibrating force thereon. Y

4. Apparatus for efi transformation of electrical and mechamcal energy into sound vibrations, comprising a resonant acoustic member supported along two curved lines,.. one within the other; said member having, in a direction acrom connecting lines betweensuch curved lines, difierent natural periods within the acoustic range; and means positively contacting-with the acoustic member fior exerting a vibrating force thereon.

5. Apparatus according to claim 3, in which the force-exerting. member is positively connected to the acoustic member along a circular line.

In testimony whereof I aflix my signature.

' ADRIMIUS AINOLDUS IAIINUS ANTONIUS KALIEUEIL lines between such circles, different 

